He said many of the long-term unemployed could not be bothered to get out of bed in time.

Ken Livingstone warned of a "whole generation being left behind". He said many of the thousands of jobs being created by the booming London economy were being snapped up by Poles and other immigrants who have a work ethic and better skills.

His comments echo those by the Mayor of Newham, Sir Robin Wales, who warned that many Londoners were too idle to take advantage of jobs promised by the 2012 Olympics.

Mr Livingstone, in his annual State of London address, said jokes about Polish plumbers or the Games being built by Poles matched the reality of them being willing and able to do the work. He contrasted this with the situation for many Londoners who have been out of work for a long time.

The Mayor said: "What we have got is a great mismatch. People have been left so far behind that they get sacked from j obs because they turn up late in the morning.

"They have grown up their entire life in a house where nobody gets up before midday. We have really got to tackle this from scratch... otherwise a whole generation is going to be left behind."

He said the situation was typified on his daily journey to City Hall when he stops to buy a coffee. "In seven years I have only been served coffee once by a born and bred Londoner," he said. "Everybody else has come from abroad to take these jobs."

The Mayor has set up a new skills taskforce that is expected to demand a root-and-branch review of post-school training and vocational courses. School leavers can choose from 80,000 courses but Mr Livingstone believes that many fail to prepare teenagers for London's jobs market, now dominated by financial services rather than manufacturing.

The Mayor wants the taskforce's recommendations, expected by the end of the year, to lead to a radical change in the "backward thinking" of careers advisers in secondary schools.

He said: "It would be absolute madness for schools not to recognise that [modern skills advice] is what they have to be giving to the pupils that are coming through. All our early studies showa backward thinking of people in careers advice. They see a young girl coming through the door and they think, 'caring, teaching, nursing'. This is ridiculous. This presumption about where you steer women to work has got to go."

The event, at the QEII Conference Centre on Saturday, heard that progress was being made employing Londoners on the Olympics.

Manny Lewis, chief executive of the London Development Agency, said that contractor Murphy, which is digging two huge tunnels to allow power lines to be buried under the Olympic Park in Stratford, had just taken on its 100th local worker - meaning one in three employed on the project comes from London.